I am using a LinkedHashMap and the environment is multi threaded so this structure needs to be thread safe. During specific events I need to read the entire map push to db and clear all.
Most of time only writes happen to this map. This map has a limit 50 entries.
I am using Oracle MAF and it does not have Collections.syncronizedMap available. So, what are things I need to put in synchronized blocks to make sure writing and reading doesn't hit me concurrentModificationException etc
Few requirements:
I need to behave it like a circular queue so Overriding removeEldestEntry method of the LinkedHashMap.
I need to preserve the order
解决方案
So, what are things I need to put in synchronized blocks to make sure writing and reading doesn't hit me concurrentModificationException etc
Everything method call should be in a synchronized block.
The tricky one being the use of an Iterator, as you have to hold the lock for the life of the Iterator. e.g.
// pre Java 5.0 code
synchronized(map) { // the lock has to be held for the whole loop.
for(Iterator iter = map.entrySet().iterator(); iter.hashNext(); ) {
Map.Entry entry = iter.next();
String key = (String) entry.getKey();
MyType value = (MyType) entry.getValue();
// do something with key and value.
}
}